by By Laura Petrecca, USA TODAY

by By Laura Petrecca, USA TODAY

British police have identified 38 "persons of interest" in their search for clues about what happened to Madeleine McCann, a young girl who disappeared in May 2007 from a holiday resort in Portugal.

Twelve of the individuals are British. The rest are from a variety of European countries, the Metropolitan Police Service said Thursday.

The police also said Thursday that Madeleine could possibly still be alive.

"Over the coming months we will be conducting assertive (inquiries), with the assistance of host countries to establish more information about the individuals concerned and any potential involvement," the police said in a statement. They also said that the case has moved from a review status to a full investigation.

"This process has been complex and issues such as translation of material have presented particular challenges," police said in a statement. "To date, some 30,500 documents have entered into the process."

The review has "generated new findings and new witness evidence."

McCann vanished from a vacation home in Praia da Luz, Portugal just days before her fourth birthday. British police said that they are in close contact with her parents, Kate and Gerry McCann, who remain active in the search for their daughter.

"We remain as determined as ever to find her and to know what has happened," Madeleine's parents wrote on FindMadeleine.com on May 2, 2013, the day before the sixth anniversary since her disappearance. FindMadeleine.com is a website dedicated to raising awareness and funds to help locate Madeleine.

Contributing: The Associated Press

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